First of all, call your carrier and ask nicely, if your contract has expired, they'll hopefully unlock your phone for you.
If you tell your carrier you'll be travelling and wish to use
a SIM card from another country to save on roaming fees, they may also unlock your phone for you.

Typically all networks impose one, two of three limits on unlocking - time after activation to unlock, cost of unlocking and how long it will take to carry out. We'll explain how to do it on all the UK's major networks. There is no need to ever use a dodgy high street 'mobile phone unlocking' service - anything they'll do you can do yourself for a fraction of the cost.

Lenovo A369i Unlock Code Number

You can also unlock screen code and sim-card of Lenovo A369i mobile phone. But you need to do first unlock code for it's operating system.

Lenovo A369i Unlock Codes :

11410199/1921140

76813113/384534

7285540/936594

7925828/540174

79216027/660534

16027534/660792

If the unlocking code is not working for Lenovo A369i, you need to enter your phone IMEI number to the box to get new one.

Sample IMEI number : 4235/234234/23422

You unlock your phone mostly the same way you would if you were doing it through your carrier. You contact an unlocking service and pay their fee (usually between $20 and $30) and they send you a code. When you insert your new SIM card, you use this code to unlock the SIM.

Note:
Cell phone unlocking is now legal in the US. However, if you live in another country or are willing to be a rebel and flout a law everyone agrees should be changed, you can often unlock phones on your own without anyone's permission. The exact process will vary from phone to phone, so you'll have to perform a web search and find instructions for your specific mobile phone.